GB1510909A - Plasma-arc-remelting - Google Patents

Abstract

1510909 Plasma-arc melting of consumable electrodes INST ELEKTROSVARKI IM E O PATONA 25 Oct 1976 44206/76 Addition to 1303415 Heading H5H [Also in Division B3] The hollow consumable electode 2 of the Parent Specification is mounted on the end of a plasma torch 3 so that plasma forming gas from a supply system 10 passes along a hollow rod 5 supporting torch 3, through torch 3 and emerges from electrode 2. As the electrode 2 melts the plasma zone between it and the molten pool in mould 1 moves upwards and the electrode 2 is moved downwards by vertical travel mechanism 7 which is connected thereto by rod 5 As shown, the a.c. source is initially connected between mould 1 and the electrode 2 which is mounted on the end of torch 3 by lamp 4 until the electrode 2 has been substantially consumed. At this point a switch 15 is actuated to interrupt the supply of current to electrode 2 and connect the plasma torch 3 in circuit. The plasma torch 3 supplies reduced heat to the ingot which eliminates the formation of damaging shrinkage cavities. In Fig. 2, not shown, the electrode 2-mould 1 has one supply and the torch 3 a separate supply. In this arrangement the torch 3 is energized throughout the process, initially to preheat the plasma forming gas supplied to consumable electrode 2, and finally, when the supply to the electrode 2 is cut off to eliminate shrinkage activities in the ingot.